Ultrasound face scanning and identification apparatuses and methods

ABSTRACT

An electronic face-identification device, which performs face scanning with ultrasonic waves, includes a housing and an ultrasound device disposed within the housing. The ultrasound device may be configured to transmit ultrasonic waves through air to a face and scan the face with the ultrasonic waves, to receive reflected waves through the air corresponding to reflections of the ultrasonic waves from the face, and to perform a recognition process for the face based on reflections of the ultrasonic waves from the face. The ultrasound device may include a plurality of ultrasound transducers, and electronic circuitry configured to transmit signals to the ultrasound transducers and receive signals from the ultrasound transducers. The face-identification device may be incorporated into various electronic equipment, such as hand-held equipment in the form of smartphones and tablet computers, as well as in larger scale installations at airports, workplace entryways, and the like.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims the benefit under 35 U.S.C. § 119(e) of U.S.Provisional Patent Application Ser. No. 62/841,114, filed Apr. 30, 2019,and entitled “ULTRASOUND FACE SCANNING AND IDENTIFICATION APPARATUSESAND METHODS,” which is hereby incorporated herein by reference in itsentirety.

FIELD OF THE DISCLOSURE

The present application relates generally to apparatuses and methodsthat use ultrasound imaging technology, and more specifically toapparatuses and methods that use ultrasound sensors to scan and identifya face.

BACKGROUND

Ultrasound systems may be used to perform diagnostic testing and imagingon an object, using acoustic or sound waves with frequencies that arehigher than those audible to humans. Such testing and imaging may beperformed non-destructively on the object. That is, the object need notundergo a physical transformation in order to be evaluated usingultrasonic sound waves. Sound waves classified as “ultrasonic” may havea frequency in a range of 20 kHz to 50 MHz.

When sound waves are transmitted into a body structure, such as that ofa living mammal, at least some of the sound waves reflect offsoft-tissue organs and other objects in the body structure, withdifferent tissues and objects reflecting varying degrees of the soundwaves. The reflected sound waves may be transformed into an electricalsignal, which may then be recorded and displayed as an ultrasound image.The strength or amplitude of the reflected sound waves, and the delay ortime it takes for the sound waves to travel to and reflect from theorgans and other objects of the body structure, provide information thatmay be used to produce the ultrasound image. Different types of imagescan be formed using ultrasound technology. For example, images can begenerated that show two-dimensional cross-sections of tissue, bloodflow, motion of tissue over time, the location of blood, the presence ofspecific molecules, the stiffness of tissue, and the anatomy of athree-dimensional region.

Some ultrasound imaging devices may be fabricated using micromachinedultrasound transducers, which may include a flexible membrane suspendedabove a substrate. A cavity may be located between part of the substrateand the membrane, such that the combination of the substrate, thecavity, and the membrane may form a variable capacitor. When actuated byan appropriate electrical signal, the membrane may generate anultrasound signal (i.e., ultrasonic waves) by vibration. Similarly, inresponse to receiving an ultrasound signal (i.e., ultrasonic waves), themembrane may vibrate and, as a result, may generate an electrical signalthat in turn may be outputted for further processing.

SUMMARY OF THE DISCLOSURE

Ultrasound face scanning and identification apparatuses and methods aredescribed. In some aspects of the present technology, an ultrasounddevice may be disposed within a housing and may be configured to scan aface with ultrasonic waves and to perform a recognition process for theface (i.e., facial recognition) based on reflections of the ultrasonicwaves from the face. The ultrasound device may include anultrasound-on-a-chip device having microfabricated ultrasoundtransducers integrated with electronic circuitry. The electroniccircuitry may be integrated circuitry of a complementary metal oxidesemiconductor (CMOS) substrate. The ultrasound device may be part of aportable electronic device (e.g., smartphone, tablet computer, laptopcomputer, etc.) for which face identification is desired periodically,or may be part of an installation that routinely performs face scanningand/or identification, such as, for example, for airport securityscreening, for motor-vehicle licensing operations, for workplacebuilding-access screening, etc.

According to an aspect of the present technology, an electronic deviceable to perform face scanning and identification may be comprised of ahousing and an ultrasound face-identification device disposed within thehousing. The ultrasound face-identification device may be configured toscan a face with ultrasonic waves and to perform a recognition processfor the face based on reflections of the ultrasonic waves from the face.

The ultrasound face-identification device may be comprised of aplurality of ultrasound transducers and electronic circuitry configuredto transmit signals to the ultrasonic transducers and receive signalsfrom the ultrasound transducers. For example, the ultrasound transducersmay be integrated on a single semiconductor chip, and may be part of anultrasound-on-a-chip device. The electronic circuitry also may beintegrated on the single semiconductor chip as part of theultrasound-on-a-chip device. Alternatively, the electronic circuitry maybe disposed on at least one semiconductor chip separate from the singlesemiconductor chip.

The ultrasound face-identification device may be configured to transmitultrasonic waves through air to the face. The ultrasoundface-identification device also may be configured to receive reflectedwaves, which correspond to reflections of the ultrasonic wavestransmitted through air and reflected from the face.

The electronic device may further be comprised of a memory deviceconfigured to store data of a reflection pattern corresponding to aperson, or to store data of a plurality of reflection patternscorresponding to a plurality of persons. The electronic circuitry may beconfigured to compare the reflection pattern(s) stored in the memorydevice with a pattern corresponding to the reflected waves received bythe ultrasound face-identification device.

According to another aspect of the present technology, a smartphonedevice able to perform ultrasound face scanning and identification maybe comprised of a housing and an ultrasound device disposed within thehousing. The ultrasound device may be configured to scan a face of auser with ultrasonic waves, and to perform a recognition process basedon reflections of the ultrasonic waves from the face. The ultrasounddevice may be comprised of a plurality of ultrasound transducers andelectronic circuitry configured to transmit signals to the ultrasoundtransducers and receive signals from the ultrasound transducers. Theelectronic circuitry may control the ultrasound transducers to perform asector scan of the face, to perform a plurality of sector scans of theface to produce a 3D scan, or to perform an area scan of the face toproduce a 3D scan.

The ultrasound transducers may be configured to transmit ultrasonicwaves through air to the face. The ultrasound transducers also may beconfigured to receive reflected waves through air, with the reflectedwaves corresponding to reflections of the ultrasonic waves transmittedthrough air and reflected from the face.

The smartphone device may further be comprised of a memory deviceconfigured to store data of a reflection pattern corresponding to theuser. The electronic circuitry may be configured to compare thereflection pattern stored in the memory device with a patterncorresponding to the reflected waves received by the ultrasound device,to determine whether the user is authorized to access restrictedfunctions of the smartphone.

According to a further aspect of the present technology, an ultrasoundidentification method may be comprised of: scanning a face usingultrasonic waves transmitted from ultrasound transducers of anelectronic device, with the ultrasonic waves being transmitted throughair to the face; receiving reflected waves through air, with thereflected waves corresponding to the ultrasonic waves transmittedthrough air and reflected from the face; and comparing a patterncorresponding to the reflected waves to a stored reflection patterncorresponding to a known face. The stored reflection pattern may beobtained from a memory device of the electronic device.

The scanning may involve utilizing ultrasound transducers configured tooperate in at least one frequency range selected from: 50 kHz to 100kHz, 100 kHz to 200 kHz, 200 kHz to 300 kHz, 300 kHz to 400 kHz, and 400kHz to 500 kHz.

The scanning may involve performing a sector scan of the face, orperforming a plurality of sector scans of the face to produce a 3D scan,or performing an area scan of the face to produce a 3D scan.

The electronic device may be a portable electronic device having adisplay screen. The scanning may involve transmitting the ultrasonicwaves through the display screen. The ultrasound identification methodmay further be comprised of performing a calibration operation todetermine transmission and reception artifacts due to irregularities ofthe display screen. The irregularities may be comprised of one or bothof: surface irregularities of the display screen, and internalirregularities of a material forming the display screen. Based on thecalibration operation, the method may further be comprised ofcompensating for the irregularities by controlling one or both of aphase and a timing of an ultrasonic wave emitted from individual ones ofthe ultrasound transducers, to cause ultrasonic waves having uniformwavefronts to be transmitted to the face. Also, based on the calibrationoperation, the method may be comprised of compensating for theirregularities by correcting the reflected waves received from the face.

BRIEF DESCRIPTION OF THE DRAWINGS

Various aspects and embodiments of the application will be describedwith reference to the following figures. It should be appreciated thatthe figures are not necessarily drawn to scale. Items appearing inmultiple figures may be indicated by the same reference number in someor all of the multiple figures in which they appear.

FIG. 1 illustrates a view of an electronic device utilizing ultrasonicwaves to identify a face, according to an embodiment of the presenttechnology.

FIGS. 2A and 2B show views of a smartphone that may be used to identifya face using ultrasonic waves, according to an embodiment of the presenttechnology.

FIGS. 3A and 3B show views of an installation that may be used toidentify a face using ultrasonic waves, according to an embodiment ofthe present technology.

FIGS. 4A and 4B show views of another installation that may be used toidentify a face using ultrasonic waves, according to an embodiment ofthe present technology.

FIG. 5A illustrates an exploded view of an electronic device accordingto an embodiment of the present technology.

FIG. 5B illustrates an assembled view of the electronic device of FIG.5A.

FIG. 6 illustrates a cross-sectional view of a portion of a smartphoneaccording to an embodiment of the present technology.

FIGS. 7A, 7B, and 7C illustrate cross-sectional view of capacitivemicromachined ultrasound transducers (CMUTs) according to variousembodiments of the present technology.

FIG. 8 illustrates an array of ultrasound transducers according to anembodiment of the present technology.

FIG. 9 illustrates an arrangement of components of an ultrasoundface-identification device according to an embodiment of the presenttechnology.

FIGS. 10A and 10B illustrate a calibration procedure according to anembodiment of the present technology.

DETAILED DESCRIPTION

Ultrasound face scanning and identification apparatuses and methods aredescribed. In some aspects of the present technology, an ultrasoundface-identification device may be disposed within a housing and may beconfigured to scan a face with ultrasonic waves and to perform anidentification process for the face based on reflections of theultrasonic waves from the face.

The ultrasound face-identification device may include anultrasound-on-a-chip device having microfabricated ultrasoundtransducers integrated with electronic circuitry on a single chip. Theelectronic circuitry may be integrated circuitry of a CMOS substrate.

The ultrasound face-identification device may be part of a portable orhand-held electronic device, such as a smartphone, a tablet computer, alaptop computer, and the like, for which face identification is desiredperiodically, such as for authentication purposes, for example.Alternatively, the ultrasound face-identification device may be part ofan installation that routinely performs face scanning and/oridentification, such as for airport security screening, formotor-vehicle licensing operations, and for workplace building-accessscreening, for example.

Exterior surface characteristics of a solid object may be evaluatedusing ultrasonic waves. When acoustic or sound waves are launched ortransmitted to a solid object, at least some of the sound waves mayreflect off the object's outer or exterior surfaces. (The terms“external” and “exterior” may be used interchangeably herein. The terms“internal” and “interior” may be used interchangeably herein.) Thestrength or amplitude of the sound waves reflected from one or more ofthe exterior surfaces, and the delay or time it takes for the soundwaves to travel to and reflect or echo from the exterior surface(s), maybe used to obtain information about the object's exterior surface(s),such as an overall exterior shape of the object. Also, information maybe obtained about variations in density and/or other physicalcharacteristics of the object's exterior surface(s) (e.g., scar tissue),which may manifest as variations in reflection characteristics of thesound waves that reflect from the exterior surface(s).

Ultrasonic waves may be produced using a transducer (ultrasoundtransducer) manufactured using known microfabrication techniques. Forexample, the ultrasound transducer may include a flexible membranesuspended above a cavity in a substrate, forming a variable capacitor.When actuated by an appropriate electrical signal, the membrane maygenerate ultrasonic waves by vibration. These sound waves may belaunched toward an object to be imaged and/or tested, and reflectedsound waves may cause the membrane of the ultrasound transducer (or amembrane of a different ultrasound transducer) to vibrate. Thevibrations may be transformed into an electrical signal for imaging orfurther testing.

The object may be a face of a person (e.g., “Person A”), and acousticreflection characteristics of the face may be used to determine anidentity of the person. In other words, the acoustic reflectioncharacteristics from the face may be used to determine that Person Acorresponds to the face.

Pulses of ultrasonic sound waves launched toward a face may give rise toa specific echo or acoustic reflection pattern corresponding to soundwaves that reflect off the face. Facial features such as cheekboneshape, location and shape of eye(s), shape and height of nose, etc., maybe unique to each person and thus the pattern of sound waves reflectedfrom the face may be used to identify the person to whom the facebelongs.

For example, the reflection pattern determined for a face may becompared with a stored reflection pattern for a known person, such as anowner of a smartphone having ultrasound face-identificationfunctionality. The reflection pattern may be used to authenticate that auser of the smartphone as its owner, and to enable access to restrictedsmartphone applications. That is, when the stored reflection patterncorresponding to the owner of the smartphone device is determined tomatch the reflection pattern of the face of the user of the smartphonedevice, then the restricted smartphone applications may be unlocked.

In another example, the reflection pattern obtained from Person B's facemay be compared with stored reflection patterns in a databasecorresponding to a known group of employees of a company. The reflectionpattern from Person B's face may be used to confirm whether Person B maygain access to the company's workplace premises (e.g., a building or aroom in a building). That is, when one of the stored reflection patternsis determined to match the reflection pattern from the face of Person B,then Person B may be given entry to the workplace premises.

In a further example, the reflection pattern obtained from Traveler C'sface may be compared with stored reflection patterns in a databasecorresponding to a known group of people. The reflection pattern fromTraveler C's face may be used to confirm whether Traveler C may gainaccess to a transportation vehicle (e.g., a train, an airplane, a ship,etc.). That is, the stored reflection patterns may be for people withrestricted travel privileges. When one of the stored reflection patternsis determined to match the reflection pattern from Traveler C's face,then Traveler C may be denied entry to the transportation vehicle.

In another example, the reflection pattern obtained from Driver D's facemay be compared with stored reflection patterns in a databasecorresponding to a state's licensed drivers. The reflection pattern fromDriver D's face may be used to confirm whether Driver D is one of thelicensed drivers of the state if, for example, Driver D is involved inan automobile incident.

The presence of cosmetics or makeup can mask facial features in anoptical image of a face. For example, when imaged optically, a person'snose may appear narrower than in reality, or the person's cheekbones mayappear higher than in reality. That is, through the use of creativelyapplied shadowing makeup, optical illusions may be created that cause anoptical image of the person's face to be different from the person'sface in reality. This is because an optical image of a face providestwo-dimensional information about the face. Depth information (e.g.,information on the height of the tip of the nose relative to the heightof the base of the nose) is not easily or reliably obtained from anoptical image of the face. Optical images therefore are flawed vehiclesfor performing face identification.

In contrast to information obtainable from conventional optical images,information obtainable from scanning a face with ultrasonic waves mayyield three-dimensional data on the scanned face, such as the relativeheights of various features of the face. That is, because there is atime component involved in the transmission of ultrasonic waves to aface, and the reflection of the ultrasonic waves from various surfacesof the face, the time component (e.g., time delay) may be used todetermine distance and hence height of the various surfaces of the face.

The presence of facial hair can mask facial features in an optical imageof a face. For example, when imaged optically, a mustache may mask theshape of a person's lip area, and a beard may mask the shape of aperson's jaw area. When a significant portion of the face is obscured byfacial hair, optical images cannot be used reliably for performing faceidentification.

In contrast, although ultrasonic waves launched toward a face mayexperience some attenuation from facial hair before reaching thesurfaces of the face, and although reflections of the ultrasonic wavesmay face some attenuation from the facial hair after reflecting from thesurfaces of the face, scanning a face with ultrasonic waves may yieldsufficient data to enable three-dimensional determination of therelative heights of various features of the face. Therefore, foridentification purposes, scanning a face with ultrasonic waves may yieldthree-dimensional data that is more reliable than what is possible withconventional, two-dimensional optical imaging. This may be especiallytrue when combined with other traditional face identificationapproaches, such as 2D and 3D optical topographical mapping withstructured illumination or multi-view stereo computer-vision techniques,and/or Fourier/principal component analysis (PCA) of 2D optical images.

According to an embodiment of the present technology, an electronicdevice may be comprised of a housing and an ultrasound device disposedwithin the housing. The ultrasound device may be configured to scan aface with ultrasonic waves and to perform a recognition process for theface based on reflections of the ultrasonic waves from the face.

In an aspect of the embodiment, the ultrasound device may be comprisedof a plurality of ultrasound transducers and electronic circuitryconfigured to transmit signals to the ultrasound transducers and receivesignals from the ultrasound transducers. The ultrasound transducers maybe integrated on one chip. For example, the ultrasound device may be anultrasound-on-a-chip device in which the ultrasound transducers areintegrated on a single semiconductor chip.

In an aspect of the embodiment, the ultrasound device may be anultrasound-on-a-chip device in which the ultrasound transducers and theelectronic circuitry are integrated on the single semiconductor chip.

Alternatively, in an aspect of the embodiment, the electronic circuitrymay be disposed on at least one semiconductor chip separate from theultrasound transducers.

In an aspect of the embodiment, the ultrasound device may be configuredto transmit ultrasonic waves through air to the face, and to receivereflected waves through air. The reflected waves may correspond to thereflections of the ultrasonic waves transmitted through air andreflected from the face.

In an aspect of the embodiment, the electronic device may be furthercomprised of a memory device configured to store data of a reflectionpattern corresponding to a person, or to store data of a plurality ofreflection patterns corresponding to a plurality of persons. Theelectronic circuitry may be configured to compare a reflection patterncorresponding to the reflected waves received by the ultrasound deviceto the reflection pattern(s) stored in the memory device.

In an aspect of the embodiment, the electronic device may be furthercomprised of a transmitter configured to transmit a patterncorresponding to the reflected waves to an external processor. Theexternal processor may operate to determine whether the patterncorresponding to the reflected waves matches a pattern stored in anexternal memory device coupled to the processor. Optionally, theelectronic device may be further comprised of a receiver configured toreceive information on whether the pattern corresponding to thereflected waves matches a pattern stored in the external memory device.

In an aspect of the embodiment, the ultrasound transducers may beconfigured to operate in one frequency range or a plurality of frequencyranges. The frequency range(s) may be selectable and may be comprised ofany one or any combination of: a 50 kHz to 100 kHz range, a 100 kHz to200 kHz range, a 200 kHz to 300 kHz range, a 300 kHz to 400 kHz range, a400 kHz to 500 kHz range. A frequency range may be selected based on atype of face scan to be performed (e.g., fine scan of detailed features,coarse scan of general features, etc.) and/or an environment in which aface scan is to be performed (e.g., temperature, humidity, etc.).

For example, when attenuation of ultrasonic waves in air may be aconcern, a lower frequency range of 50 kHz to 100 kHz may be selectedfor the ultrasonic waves. In this lower frequency range, with the speedof sound in air taken to be 343 m/s, attenuation of ultrasonic waves inair may be approximately 1.2 dB/m. However, in this frequency range, thespatial resolution may be in the range of approximately 3 mm to 7 mm.

In another example, when attenuation of ultrasonic waves in air may notbe a concern, a higher frequency range of 300 kHz to 500 kHz may beselected for the ultrasonic waves. In this higher frequency range, thespatial resolution may be in the range of approximately 0.7 mm to 1.1mm. However, in this higher frequency range, attenuation of ultrasonicwaves in air may be approximately 35 dB/m.

The electronic circuitry may be configured to enable a user to select anoperating frequency within a selected one of the frequency ranges. Forexample, the electronic circuitry may be configured to control theultrasound transducers to perform an initial lower-resolution scan at arelatively lower frequency of one frequency range and a subsequenthigher-resolution scan at a relatively higher frequency of anotherfrequency range.

As will be appreciated, there are tradeoffs between frequency,resolution, and attenuation. For situations where ultrasonic waves neednot travel very far to reach a face to be scanned (e.g., when the faceis within about 6 inches to 12 inches of a smartphone incorporating anultrasound device according to various embodiments of the presenttechnology), then higher frequencies may be more desirable becauseattenuation of the ultrasonic waves in air is not a significant concerndue to the short transit distance to and from the face. On the otherhand, for situations where ultrasonic waves need to travel relativelylonger distances to reach a face to be scanned (e.g., when the face is afew feet from an installation incorporating an ultrasound deviceaccording to various embodiments of the present technology), then lowerfrequencies may be more desirable because attenuation of the ultrasonicwaves may cause difficulty in obtaining a reliable scan of the face.

TABLE 1 includes data that may be relevant in choosing a frequency rangefor scanning a face.

TABLE 1 Acoustic Frequency  50 kHz to 100 kHz 100 kHz to 200 kHz 300 kHzto 500 kHz Timing Resolution 10 μs to 20 μs  5 μs to 10 μs 2.0 μs to 3.3μs Phase Resolution ~1.5 cm ~1 cm ~0.5 cm Attenuation in Air ~1.2 dB/m~3 dB/m ~35 dB/m Wavelength (λ) ~3.4 mm to 6.9 mm   ~1.7 mm to 3.4 mm  ~700 μm to 1.1 mm    Transducer Diameter ~1.5 mm to 2.5 mm   ~1.1 mm to1.2 mm   ~560 μm to 600 μm     Spacing Between ~2.5 mm to 5 mm     ~1 mmto 2 mm   ~500 μm to 1 mm     Transducers (λ/2 to λ) Transducer ~20 μm~10 μm ~10 μm Membrane Thickness

In an aspect of the embodiment, the electronic circuitry may control theultrasound transducers to perform a sector scan of the face, or toperform a plurality of sector scans of the face to produce athree-dimensional (3D) scan. A sector scan may be analogous to a B-scanused in medical ultrasound imaging, where a trace or line is scannedalong the face to obtain a “slice” of information about the face. Forexample, a vertical sector scan may be performed near a centerline ofthe face, to capture reflections from facial features such as theforehead, the nose, the lips, and the chin. Multiple sector scans alongthe face may be combined to yield a 3D scan, yielding depth informationin addition to two-dimensional position information. With this aspect ofthe embodiment, the ultrasound transducers may be arranged in aone-dimensional array or line, and may be controlled to emit ultrasonicwaves in unison.

In an aspect of the embodiment, the electronic circuitry may control theultrasound transducers to perform an area scan of the face to produce a3D scan. With this aspect of the embodiment, the ultrasound transducersmay be arranged in a two-dimensional array and may be controlled to emitultrasonic waves in unison, in subgroups, or individually. The phasesand launch or firing times of the ultrasound transducers may beindividually controlled by the electronic circuitry so that theultrasonic waves have desired wavefront characteristics. For example,the phases may be controlled so that the wavefront has a desired anglerelative to the face. Optionally, the ultrasound transducers may beindividually controlled to control their phases and launch times inorder to compensate for irregularities in, for example, a display screenthrough which the ultrasonic waves must travel, as discussed below.

According to an embodiment of the present technology, an electronicdevice may be comprised of a housing and an ultrasound device disposedwithin the housing. The housing may include a display screen. Theultrasound device may be configured to scan a face with ultrasonic wavesand to perform a recognition process for the face based on reflectionsof the ultrasonic waves from the face. For example, the ultrasounddevice may be configured to scan the face by transmitting ultrasonicwaves through the display screen.

In an aspect of the embodiment, the ultrasound device may be comprisedof an array of ultrasound transducers facing toward an internal surfaceof the display screen, and electronic circuitry coupled to the array totransmit signals to the ultrasound transducers and receive signals fromthe ultrasound transducers. The array may be a one-dimensionalarrangement of the transducers or a two-dimensional arrangement of theultrasound transducers.

In an aspect of the embodiment, the electronic circuitry may beconfigured to control the ultrasound transducers to perform acalibration operation to determine transmission and reception artifactsdue to irregularities of the display screen. The irregularities may becomprised of surface irregularities of the display screen and/orinternal irregularities of a material forming the display screen. Basedon the calibration operation, the electronic circuitry may compensatefor the irregularities by controlling one or both of a phase and alaunch time of an ultrasonic wave emitted from individual ones of theultrasound transducers, to cause ultrasonic waves having, for example, auniform wavefront to be transmitted to the face. As will be appreciated,other types of wavefronts may be used, including non-uniform wavefronts.Optionally, based on the calibration operation, the electronic circuitrymay compensate for the irregularities by correcting the signals receivedfrom the ultrasonic transducers. ultrasound

According to an embodiment of the present technology, a smartphone thatperforms ultrasound face identification may be comprised of a housingand an ultrasound device disposed within the housing. The ultrasounddevice may be configured to scan a face of a user with ultrasonic wavesand to perform an identification process based on reflections of theultrasonic waves from the face.

In an aspect of the embodiment, the ultrasound device may be comprisedof a plurality of ultrasound transducers and electronic circuitryconfigured to transmit signals to the ultrasound transducers and receivesignals from the ultrasound transducers. The electronic circuitry may beconfigured to control the ultrasound transducers to perform a sectorscan of the face. Optionally, the electronic circuitry may be configuredto control the ultrasound transducers to perform a plurality of sectorscans of the face, to produce a 3D scan. In another option, theelectronic circuitry may be configured to control the ultrasoundtransducers to perform an area scan of the face, to produce a 3D scan.

In an aspect of the embodiment, the ultrasound transducers may beconfigured to transmit ultrasonic waves through air to the face, and toreceive reflected waves through air. The reflected waves may correspondto the reflections of the ultrasonic waves transmitted through air andreflected from the face.

In an aspect of the embodiment, the smartphone may be further comprisedof a memory device configured to store data of a reflection patterncorresponding to the user. The electronic circuitry may be configured tocompare the reflection pattern stored in the memory device with apattern corresponding to the reflected waves received by the ultrasounddevice, to determine whether the user is authorized to access restrictedfunctions of the smartphone.

In an aspect of the embodiment, the ultrasound transducers may beconfigured to operate in one frequency range or a plurality of frequencyranges. The frequency range(s) may be selectable and may be comprisedof: a 50 kHz to 100 kHz range, a 100 kHz to 200 kHz range, a 200 kHz to300 kHz range, a 300 kHz to 400 kHz range, and a 400 kHz to 500 kHzrange.

In an aspect of the embodiment, the ultrasound transducers may becomprised of multiple subsets of transducers. The transducers of onesubset may be different from the transducers of another subset. Forexample, the transducers of one subset may have a relatively smallerspacing between transducers, and the transducers of another subset mayhave a relatively larger spacing between transducers. Each frequencyrange of the ultrasound device may utilize a different subset of theultrasound transducers, although some of the ultrasound transducers maybelong to more than one of the subsets.

According to an embodiment of the present technology, a smartphone thatperforms ultrasound face identification may be comprised of a housingand an ultrasound device disposed within the housing. The housing may becomprised of a display screen. The ultrasound device may be configuredto scan a face of a user with ultrasonic waves and to perform arecognition process based on reflections of the ultrasonic waves fromthe face. For example, the ultrasound device may be configured to scanthe face by transmitting ultrasonic waves through the display screen.

In an aspect of the embodiment, the ultrasound device may be comprisedof an array of ultrasound transducers facing toward an internal surfaceof the display screen, and electronic circuitry coupled to the array totransmit signals to the ultrasound transducers and receive signals fromthe ultrasound transducers. For example, the array may be aone-dimensional arrangement of the ultrasound transducers, or may be atwo-dimensional arrangement of the ultrasound transducers.

In an aspect of the embodiment, the electronic circuitry may beconfigured to control the ultrasound transducers to perform acalibration operation to determine transmission and reception artifactsdue to irregularities of the display screen. The irregularities may becomprised of surface irregularities of the display screen and/orinternal irregularities of a material forming the display screen. Basedon the calibration operation, the electronic circuitry may compensatefor the irregularities by controlling one or both of a phase and atiming of an ultrasonic wave emitted from individual ones of theultrasound transducers, to cause ultrasonic waves having a desiredwavefront to be transmitted to the face. The desired wavefront may havea uniform shape or may have a non-uniform shape. Optionally, based onthe calibration operation, the electronic circuitry may compensate forthe irregularities by correcting the signals received from theultrasound transducers.

According to an embodiment of the present technology, an ultrasoundidentification method may be comprised of: scanning a face usingultrasonic waves transmitted from ultrasound transducers of anelectronic device, with the ultrasonic waves being transmitted throughair to the face; receiving reflected waves through air, with thereflected waves corresponding to the ultrasonic waves transmittedthrough air and reflected from the face; and comparing a patterncorresponding to the reflected waves to a stored reflection patterncorresponding to a known face.

In an aspect of the embodiment, the stored reflection pattern may beobtained from a memory device of the electronic device.

In an aspect of the embodiment, the scanning may involve utilizingultrasound transducers configured to operate in one or more frequencyranges. The frequency range(s) may be selectable and may be any one or acombination of: a 50 kHz to 100 kHz range, a 100 kHz to 200 kHz range, a200 kHz to 300 kHz range, a 300 kHz to 400 kHz range, and a 400 kHz to500 kHz range.

In an aspect of the embodiment, the scanning may involve performing asector scan of the face, performing a plurality of sector scans of theface to produce a 3D scan, or performing an area scan of the face toproduce a 3D scan.

In an aspect of the embodiment, the electronic device may be a portableelectronic device, and the scanning may involve transmitting theultrasonic waves through a display screen of the portable electronicdevice.

In an aspect of the embodiment, the electronic device may beincorporated in an installation that performs ultrasound face scansroutinely.

In an aspect of the embodiment, the method may be further comprised ofperforming a calibration operation to determine transmission andreception artifacts due to irregularities of the display screen. Theirregularities may be comprised of surface irregularities of the displayscreen and/or internal irregularities of a material forming the displayscreen.

In an aspect of the embodiment, the method may be further comprised of,based on the calibration operation, compensating for the irregularitiesby controlling one or both of a phase and a timing of an ultrasonic waveemitted from individual ones of the ultrasound transducers to causeultrasonic waves having uniform wavefronts to be transmitted to theface. Optionally, the method may be further comprised of, based on thecalibration operation, compensating for the irregularities by correctingthe reflected waves received from the face.

It should be appreciated that the embodiments described herein may beimplemented in any of numerous ways. Examples of specificimplementations are provided below for illustrative purposes only. Itshould be appreciated that these embodiments and thefeatures/capabilities provided may be used individually, all together,or in any combination of two or more, as aspects of the technologydescribed herein are not limited in this respect.

Turning now to the figures, FIG. 1 is a schematic view of an electronicdevice 1 that utilizes ultrasound technology to identify a face 2. Theelectronic device 1 scans the face 2 by transmitting ultrasonic waves 3toward the face 2. Reflected waves 4, which are ultrasonic waves thatreflect off the face 2 towards the electronic device 1, are received bythe electronic device 1. An electrical signal corresponding to thereflected waves 4 contains data specific to the face 2. The electricalsignal may be used to perform a recognition process for identifying theface 2.

In an embodiment of the present technology, the electronic device 1 maybe incorporated as part of a portable electronic apparatus, such as asmartphone, a tablet computer, a laptop computer, and the like, forwhich face identification is desired periodically, such as forauthentication purposes to unlock the electronic apparatus or to unlockfunctions of the apparatus. FIGS. 2A and 2B schematically show examplesof this embodiment, in which the electronic device 1 (not visible in thefigure) is incorporated in a smartphone 5. The smartphone 5 may be heldby a user 6 to scan the face 2 of the user 6 for authenticationpurposes.

In another embodiment of the present technology, the electronic device 1may be incorporated as part of an installation that routinely performsface scanning and/or identification. Such an installation may be usedfor airport security screening, for obtaining information formotor-vehicle licenses, and for workplace building-access screening, forexample. FIGS. 3A and 3B schematically show examples of this embodiment,in which the installation is a screening station 7 at an airport. FIGS.4A and 4B schematically show other examples of this embodiment, in whichthe installation is a building-access screener 8 or an entryway screener9. The electronic device 1 (not visible in the figures) may beincorporated in the screening station 7, the building-access screener 8,and the entryway screener 9 to perform face scanning and/oridentification on many different faces routinely.

FIG. 5A schematically illustrates an exploded view of a portableelectronic device 100 according to an embodiment of the presenttechnology. The portable electronic device 100 may include a housing102, a circuit board 104, an ultrasound face-scanning device 106disposed on and electrically connected to the circuit board 104, and acover 108.

The electronic device 100 may be a smartphone or other portableelectronic device. The electronic device 100 may be sized to behand-held, for instance having a long dimension M of less thanapproximately six inches. The various aspects described herein are notlimited by the particular dimensions. The electronic device 100 mayinclude electronic circuitry that provides various functions, such asmaking and receiving phone calls, sending and receiving text messages,connecting to the Internet, taking pictures, word processing, speechrecognition, and/or other functions.

The housing 102 may be configured to house the circuit board 104. Thecircuit board 104 may be a printed circuit board in some embodiments,although alternatives are possible. More generally, the circuit board104 is one non-limiting example of a substrate that may be used tosupport various components of the electronic device 100.

The ultrasound transducers of the ultrasound face-scanning device 106may be an array of capacitive micromachined ultrasound transducers(CMUTs), which may be integrated with complementary metal oxidesemiconductor (CMOS) electronic circuitry on a single semiconductor chipas part of an ultrasound-on-a-chip device, as mentioned above.Alternatively, the ultrasound transducers may be disposed on a separatechip from the electronic circuitry. As shown in FIG. 5A, the ultrasoundface-scanning device 106 may be a discrete packaged componentelectrically coupled to the circuit board 104. Other configurations arepossible, however, such as monolithically integrating the ultrasoundtransducers of the ultrasound face-scanning device 106 with othercomponents on a common substrate.

The cover 108 is configured to mate with the housing 102 and define anenclosed space in which the circuit board 104 is disposed. The cover 108may be formed of a layer of glass, or plastic, or another material thatpermits transmission of ultrasonic waves. The cover 108 may form part ofa display component of the electronic device 100. For example, the cover108 may be formed of glass, and an organic display layer may be disposedon a backside of the glass of the cover 108, an example of which isdescribed further below. The ultrasound face-scanning device 106 may beconfigured to emit and receive ultrasound signals (i.e., ultrasonicwaves) through the glass of the cover 108. In this manner, a face may bescanned with the ultrasonic waves, and reflections of the ultrasonicwaves from the face may be received and processed. In some embodiments,the ultrasound face-scanning device 106 may be configured to emit andreceive through glass, ceramic, metal, and/or organic film stacks, suchas may be present in smartphones, tablet computers, and other electronicdevices.

FIG. 5B shows an assembled view of the electronic device 100 of FIG. 5A.In this figure the electronic device 100 is a smartphone, and the cover108 is a display component of the smartphone (e.g., a touchscreendisplay). The ultrasound face-scanning device 106, which is disposedwithin an enclosed space defined by the housing 102 and the cover 108,is illustrated as a dashed box because it is not visible through thecover 108.

As mentioned above, the ultrasound face-scanning device 106 may becomprised of a plurality of ultrasound transducers. Additionally, theultrasound face-scanning device 106 may be comprised of electroniccircuitry configured to transmit signals to the ultrasound transducersand receive signals from the ultrasound transducers. The ultrasoundtransducers may be integrated on a single semiconductor chip, and theelectronic circuitry may be integrated on the same single semiconductorchip as the ultrasound transducers, as part of an ultrasound-on-a-chipdevice. Alternatively, the electronic circuitry may instead be providedon one or more semiconductor chip(s) separate from the ultrasoundtransducers.

The ultrasound face-scanning device 106 may be configured to emitultrasonic waves to outside of the cover 108, and to receive reflectedwaves, which for example may be reflected from a face positionedopposite the cover 108 or nearly opposite the cover 108. As will beappreciated, the face must be located within a distance such that evenwith attenuation of the ultrasonic waves in air, the reflected wavesprovide an electrical signal sufficient to further face-identificationprocessing. The electronic circuitry may include processing circuitryconfigured to compare a reflection pattern of the reflected waves to oneor more patterns stored in a memory device housed in the housing 102. Ifthe processing circuitry determines that there is a match between thereflection pattern of the reflected waves and a pattern stored in thememory, the processing circuitry may enable a restricted function of theelectronic device 100 to be activated.

It should be appreciated that the electronic device 100 of FIGS. 5A and5B may include additional components not illustrated. For example, theelectronic device 100 may be part of a smartphone, and the circuit board104 may include a processor, a memory device, a microphone, a speaker, acamera, a display driver, and/or other components of the smartphone.Thus, the electronic device 100 may perform functions other than facescanning. In fact, the electronic device 100 may be used, in someembodiments, primarily for functions other than face scanning. When theelectronic device 100 is a smartphone, the face-scanning functionalitymay be used, for example, to provide a user with access to additionalsmartphone functions, such as payment functions, camera functions, andother known smartphone functions.

Although not separately illustrated, in an embodiment of the presenttechnology, the ultrasound face-scanning device 106 may be incorporated,in whole or in part, in a housing of an installation instead of thehousing 102 of the electronic device 100. The ultrasound transducers ofthe ultrasound face-scanning device 106 may be positioned in theinstallation to emit ultrasonic waves toward a face positioned oppositeor near a predetermined part of the installation, and to receivereflected waves, which reflect from the face. The electronic circuitryof the ultrasound face-scanning device 106 may be positioned in theinstallation or may be located external to the installation. Forexample, if the installation is one of a group of similar installationsat a facility (e.g., an airport), the electronic circuitry may be partof an external server that receives and processes signals from multipleinstallations at the facility. In this embodiment, a reflection patterncorresponding to reflected waves from a face at one of the installationsmay be compared with a database of patterns stored in a memory deviceoperatively connected to the external server. For example, the databaseof patterns may correspond to faces of people with travel restrictions.If processing by the external server determines that there is a matchbetween the reflection pattern for the face at one of the installationsand a pattern in the database stored in the memory, the external servermay issue a notification to personnel at that installation to warn themthat the face undergoing identification processing belongs to someonewho has travel restrictions.

FIG. 6 schematically illustrates an example of a cross-section of aportion of a smartphone having face-scanning functionality, according toan embodiment of the present technology. The smartphone 600 may becomprised of a circuit board 640 electrically coupled to, and configuredto control, a display layer 620 and an array 630 of ultrasoundtransducers. The display layer 620 may be configured to produce light611 through a surface 610, which may be comprised of a transparentmaterial. For example, the transparent material may be a glassy materialor a polymeric material. The display layer 620 may be comprised alight-emitting diode (LED) display, or an organic light-emitting diode(OLED) display, or another type of display known in the art. The array630 may be configured to emit ultrasonic waves 612, and may be comprisedof any number of ultrasound transducers arranged in a layer.

As noted above, the ultrasound transducers may be configured to operatein a predetermined frequency range or in a frequency range selected froma plurality of frequency ranges. The frequency range(s) may be comprisedof any one or a combination of: a 50 kHz to 100 kHz range, a 100 kHz to200 kHz range, a 200 kHz to 300 kHz range, a 300 kHz to 400 kHz range, a400 kHz to 500 kHz range. Depending on the frequency range in operation,some of the ultrasound transducers may controlled to emit ultrasonicwaves, while others of the ultrasound transducers may be controlled tobe non-operational or to receive but not transmit ultrasonic waves. Thatis, the array 630 of ultrasound transducers may be comprised ofsub-arrays (not shown), with each of the sub-arrays configured tooperate in a frequency range different from that of another one of thesub-arrays.

As has been described herein, aspects of the present technology mayutilize capacitive micromachined ultrasound transducers (CMUTs). Variousconfigurations of ultrasound transducers and electronic circuitry forcontrolling the ultrasound transducers and/or processing signals fromthe ultrasound transducers (“control and processing circuitry”) may beemployed. Three non-limiting examples include: (a) an array of CMUTsdisposed on a semiconductor substrate separate from the control andprocessing circuitry; (b) an array of CMUTs formed of an engineeredsubstrate and integrated with a circuitry substrate; and (c) an array ofCMUTs directly integrated on a circuitry substrate through lowtemperature wafer bonding of a membrane layer on the integrated circuitsubstrate. Each of these examples is now described.

FIG. 7A illustrates a non-limiting example of a CMUT 700 that may beused in an ultrasound face-scanning device, according to variousembodiments of the present technology. As will be described furtherbelow, the illustrated CMUT 700 does not include control or processingcircuitry. Thus, an array of such transducers on one semiconductor chipmay be coupled to a separate chip or circuit board having suitablecontrol and/or processing circuitry.

The CMUT 700 is comprised of a substrate 702, an electrode 704,dielectric layers, 706, 708, 710, and a silicon layer 712. Thecombination of the dielectric layer 710 and the silicon layer 712 mayserve as a membrane above a cavity 714. The silicon layer 712 may bedoped suitably to be conducting, or an optional further electrode layer(not shown) may be disposed on the silicon layer 712. Thus, thecombination of the membrane, the cavity 714, and the electrode 704 mayform a variable capacitor, with the capacitance depending on thedistance between the membrane and the electrode 704.

The substrate 702 may be any suitable substrate. For example, thesubstrate 702 may be a semiconductor substrate formed of silicon oranother suitable semiconductive material. As described previously,although the substrate 702 may include the electrode 704 and electricalrouting layers (not shown), it may lack control circuitry and processingcircuitry for controlling operation of the CMUT 700 and for processingoutput signals from the CMUT 700. Instead, such circuitry may beprovided off-chip.

The electrode 704 may be of any material and/or shape, and may have anydimension(s) for providing desired electrical behavior, includingapplying a voltage and receiving a signal resulting from vibration ofthe membrane. In some embodiments, the electrode 704 may be shaped as aring, and thus may appear in cross-section as shown in FIG. 7A. However,other shapes are possible. The electrode 704 may be formed of a metal orother suitable conductive material.

The dielectric layers 706, 708, 710 may be formed of any suitablematerial(s) exhibiting dielectric behavior. As a non-limiting example,the dielectric layer 706 may be aluminum oxide (Al₂O₃), and thedielectric layers 708, 710 may be silicon oxide.

The silicon layer 712 may have any suitable thickness for serving as amembrane, or part of a membrane in combination with the dielectric layer710. For example, the membrane, including the silicon layer 712, mayhave a thickness less than 50 μm in some embodiments.

As described above, an alternative implementation is to form the CMUT aspart of an engineered substrate that is bonded to an integrated-circuitsubstrate with electronic circuitry. The electronic circuitry of theintegrated-circuit substrate may include circuitry representing controlcircuitry and/or processing circuitry, such as depicted in FIG. 7B.Specifically, FIG. 7B is a cross-sectional view of an example of aplurality of CMUTs 720 that include a circuitry substrate integratedwith an engineered substrate having sealed cavities, according to anembodiment of the present technology.

As shown in FIG. 7B, the CMUTs 720 include an engineered substrate 722and a circuitry substrate 724. The engineered substrate 722 includes afirst silicon layer 726, a dielectric layer 728, and a second siliconlayer 730 representing a membrane. Cavities 732 are positioned betweenthe dielectric layer 728 and the second silicon layer 730. The cavities732 are sealed by the second silicon layer 730 in this example. Theengineered substrate 722 is further comprised of insulating portions 734providing electrical insulation between conductive portions of the firstsilicon layer 726.

The circuitry substrate 724 includes integrated circuitry 738, which mayinclude control circuitry and/or processing circuitry for controllingoperation of the CMUTs 720 and/or for processing signals output from theCMUTs 720. In some embodiments, the integrated circuitry 738 is CMOScircuitry and the circuitry substrate 724 is a CMOS substrate. Theintegrated circuitry 738 may control the CMUTs 720 to emit and receivein a manner such that for a single transmit event, multiple transducersof the CMUTs 720 may emit and receive ultrasound signals. In someembodiments, multi-channel emission and reception may be performed aspart of a given transmit event, providing greater data thansingle-channel transmission and reception would. For example,multi-channel operation for a given a transmit event may facilitatecorrection of aberrations or other undesirable effects in the data. Insome embodiments, the integrated circuitry 738 may include multiplexingcircuitry. For example, the multiplexing circuitry may be configured tomultiplex transmission or reception of multiple channels.

The engineered substrate 722 and the circuitry substrate 724 may bebonded together by bonds 736. In some embodiments, the bonds 736 may beconductive, providing electrical connection between the engineeredsubstrate 722 and the integrated circuitry 738.

The CMUTs 720 may be formed using two wafer-level bonding steps. Theengineered substrate 722 may be formed by bonding a first silicon waferwith a second silicon wafer, and then annealing at high temperature toform a strong bond. The annealing temperature may be above 450° C. insome embodiments. The engineered substrate 722 may subsequently bebonded with the circuitry substrate 724 at a temperature sufficientlylow to ensure that the integrated circuitry 738 is not damaged by heatduring the subsequent bonding.

Further examples of CMUTs formed in an engineered substrate and bondedwith a circuitry substrate are described in U.S. Pat. Publication No.2018/0257927 A1, which is hereby incorporated herein by reference in itsentirety.

An alternative implementation, a CMUT 740 may be formed directly on anintegrated-circuit substrate by bonding a membrane of the CMUT 740directly to an integrated-circuit substrate, as schematicallyillustrated in FIG. 7C. As shown, the CMUT 740 has a structure that issubstantially the same as that of the CMUT 700 of FIG. 7A, except thatthe substrate 702 is replaced with an integrated-circuit substrate 742,which includes integrated circuitry 744. The integrated circuitry 744may be substantially the same as the integrated circuitry 738 of FIG.7B, and in some embodiments may perform the same functions.

The CMUT 740 of FIG. 7C may be fabricated using low-temperature waferbonding. Various structures of the integrated-circuit substrate 742 maybe fabricated, including the cavity 714. Subsequently, a wafer comprisedof the dielectric layer 710 and the silicon layer 712 may be bonded withthe integrated-circuit substrate 742 to seal the cavity 714. The bondingmay be performed at a temperature sufficiently low to ensure that theintegrated circuitry 744 is not damaged. For example, the bonding may beperformed at temperatures at or below 450° C. in some embodiments.

Further examples of CMUTs integrated with an integrated-circuitsubstrate, and having a membrane bonded directly with theintegrated-circuit substrate, are described in U.S. Pat. No. 9,242,275,which is incorporated herein by reference in its entirety.

According to various embodiments of the present technology, anultrasound face-scanning device may employ an array of CMUTs. Forexample, an array of the types of CMUTs shown in FIGS. 7A-7C may beused. FIG. 8 schematically illustrates an example of an array. As willbe appreciated, other types of arrays may be used.

FIG. 8 shows an example of a plan view of a two-dimensional array 800 ofultrasound transducers 802. The ultrasound transducers 802 may be any ofthe types previously described in connection with FIGS. 7A-7C, althoughother forms of CMUTs may be used. In the illustrated example, theultrasonic sound transducers 802 are circular and separated intotransducer cells 804. The cells 804 may have a width Win a range of 10μm to 100 μm, or 25 μm to 100 μm, or 50 μm to 75 μm, or any othersuitable range of dimensions for providing a resolution sufficient todetect facial features. The ultrasound transducers 802 may be spaced bya distance L, which may be between 1 μm and 20 μm. The membrane of oneor more of the cells 804 may have a thickness (into and out of the page)between 1 μm and 20 μm in some embodiments, and between 1 μm and 5 μm inother embodiments. The ultrasound transducers 802 may have a pitch ofany suitable value, such as within the range of values for W.

The ultrasound transducers 802 may have dimensions sufficient to operateat any one of the following frequency ranges, or any combination of thefollowing frequency ranges: a 50 kHz to 100 kHz range, a 100 kHz to 200kHz range, a 200 kHz to 300 kHz range, a 300 kHz to 400 kHz range, and a400 kHz to 500 kHz range. Although the ultrasound transducers 802 of thearray 800 are shown to be arranged in a two-dimensional array, which issuitable for some embodiments, for other some other embodiments theultrasound transducers 802 may be arranged in a line, i.e., in aone-dimensional array. When arranged in a two-dimensional array, thearray may have any suitable number of ultrasound transducers 802 alongrows and columns of the array. In some embodiments, the array may havean equal number of transducers in rows and columns, however alternativesare possible. According to embodiments of the present technology, theultrasound transducers 802 may transmit and/or receive ultrasoundsignals of frequencies assuming any value or range of values withinthose ranges listed above.

FIG. 9 schematically illustrates an example of the ultrasoundface-scanning device 106, which embodies various aspects of thetechnology described herein. The ultrasound face-scanning device 106 mayinclude a transducer array 902, a transmitter 904 (TX circuitry), areceiver 906 (RX circuitry), a controller 908, a signal processor 910,and a memory device 920. In FIG. 9, the illustrated components are shownto be located on a single circuit board 912; however, in various otherembodiments, one or more of the illustrated components may instead belocated off-board. It should be appreciated that communication betweenone or more of the illustrated components may be performed in any ofnumerous ways, e.g., via one or more high-speed busses for high-speedintra-board communication and/or communication with one or moreoff-board components.

The transducer array 902 may take on any of numerous forms, and aspectsof the present technology do not necessarily require the use of anyparticular type(s) or arrangement(s). An ultrasound transducer of thearray 902 may, for example, include CMUT, a CMOS ultrasonic transducer(CUT), a piezoelectric micromachined ultrasonic transducer (PMUT),and/or another suitable ultrasound transducer. The array 902, thetransmitter 904, and the receiver 906 may be formed on separate chips.Alternatively, a combination of the array 902 and some or all of theother components shown in FIG. 9 may be integrated on the same chip inan ultrasound-on-a-chip device. Information regarding microfabricatedultrasound transducers may be found in U.S. Pat. No. 9,067,779, which isincorporated by reference herein in its entirety.

The controller 908 may generate timing and control signals that are usedto synchronize and coordinate operation of other components of theultrasound face-scanning device 106. For example, the controller 908 mayprovide a scan-control signal to the transmitter 904 to controlgeneration and outputting of drive pulses by the transmitter 904 to thetransducer array 902, to cause the ultrasound transducers of thetransducer array 902 to emit pulses of ultrasonic waves to a face. Thecontroller 908 may be driven by a clock signal CLK supplied to an inputport 916 of the ultrasound face-scanning device 106. The drive pulsesfrom the transmitter 904 may drive the ultrasound transducers of thetransducer array 902 individually or collectively.

Reflected waves, which are reflected from surfaces of a face beingscanned, may impinge on the transducer array 902, causing the ultrasoundtransducers of the transducer array 902 to vibrate and output analogelectrical signals representing vibration data. The receiver 906 maygenerate digital electrical signals from the vibration data obtainedfrom the transducer array 902, and may provide the digital electricalsignals to the signal processor 910. The signal processor 910 mayprocess the electrical signals from the receiver 906 to generate areflection pattern.

FIGS. 10A and 10B schematically illustrate calibration operations thatmay be used to correct for irregularities in the transmission and/orreception of ultrasonic waves. The irregularities may be caused by, forexample, irregularities at the surface 610 of a display screen and/orinternal irregularities of a material forming a display layer 620 of thedisplay screen (see FIG. 6). As will be appreciated, other sources ofirregularities may be possible.

As shown in FIG. 10A, ultrasonic waves emitted from a transducer array1001 may have an initial wavefront 1002 that is uniform in shape,represented by the straight parallel lines in the figure. After passingthrough a display screen (“display & surface”), the ultrasonic waves mayhave an altered wavefront 1003 that is non-uniform in shape. Suchnon-uniformity in the altered wavefront 1003 results in the ultrasonicwaves reaching a face non-uniformly. That is, some portions of thealtered wavefront 1003 may be delayed in reaching the face due toirregularities in the display screen, which could produce distortions inthe resulting reflection pattern. By determining the shape of thealtered wavefront 1003 and then controlling the phases and the launch orfiring times of the ultrasound transducers of the transducer array 1001,the irregularities may be compensated.

As shown in FIG. 10B, by controlling the ultrasound transducers of thetransducer array 1001 to produce ultrasonic waves having an invertedwavefront 1002A, the ultrasonic waves emanating from the display screen1003 have a corrected wavefront 1004A that has known shape (e.g., auniform shape). Consequently, because the corrected wavefront 1004A hasa known uniform shape, subsequent processing of reflected waves from theface is less prone to distortion due to the irregularities.

The indefinite articles “a” and “an,” as used herein in thespecification and in the claims, unless clearly indicated to thecontrary, should be understood to mean “at least one.”

The phrase “and/or,” as used herein in the specification and in theclaims, should be understood to mean “either or both” of the elements soconjoined, i.e., elements that are conjunctively present in some casesand disjunctively present in other cases. Multiple elements listed with“and/or” should be construed in the same fashion, i.e., “one or more” ofthe elements so conjoined. Other elements may optionally be presentother than the elements specifically identified by the “and/or” clause,whether related or unrelated to those elements specifically identified.

As used herein in the specification and in the claims, the phrase “atleast one,” in reference to a list of one or more elements, should beunderstood to mean at least one element selected from any one or more ofthe elements in the list of elements, but not necessarily including atleast one of each and every element specifically listed within the listof elements and not excluding any combinations of elements in the listof elements. This definition also allows that elements may optionally bepresent other than the elements specifically identified within the listof elements to which the phrase “at least one” refers, whether relatedor unrelated to those elements specifically identified.

The terms “approximately” and “about” may be used to mean within ±20% ofa target value in some embodiments, within ±10% of a target value insome embodiments, within ±5% of a target value in some embodiments, andyet within ±2% of a target value in some embodiments. The terms“approximately” and “about” may include the target value.

The term “substantially” if used herein may be construed to mean within95% of a target value in some embodiments, within 98% of a target valuein some embodiments, within 99% of a target value in some embodiments,and within 99.5% of a target value in some embodiments. In someembodiments, the term “substantially” may equal 100% of the targetvalue.

Any reference to a numerical value being between two endpoints, if sucha reference is made herein, should be understood to encompass asituation in which the numerical value can assume either of theendpoints. For example, stating that a characteristic has a valuebetween A and B, or between approximately A and B, should be understoodto mean that the indicated range is inclusive of the endpoints A and Bunless otherwise noted.

Also, the phraseology and terminology used herein is for the purpose ofdescription and should not be regarded as limiting. The use of“including,” “comprising,” or “having,” “containing,” “involving,” andvariations thereof herein, is meant to encompass the items listedthereafter and equivalents thereof as well as additional items.

Some aspects of the present technology may be embodied as one or moremethods. The acts performed as part of the method may be ordered in anysuitable way. Accordingly, embodiments may be constructed in which actsare performed in an order different than illustrated, which may includeperforming some acts simultaneously, even though shown as sequentialacts in illustrative embodiments.

Having described above several aspects of at least one embodiment, it isto be appreciated various alterations, modifications, and improvementswill readily occur to those skilled in the art. Such alterations,modifications, and improvements are intended to be object of thisdisclosure. Accordingly, the foregoing description and drawings are byway of example only.

What is claimed is:
 1. An electronic device, comprising: a displayscreen; and an ultrasound device, further comprising: an array ofultrasound transducers that faces an internal surface of the displayscreen; electronic circuitry that is coupled to the array, wherein theelectronic circuitry transmits signals to and receives signals from theultrasound transducers such that the electronic device electronicallyscans ultrasonic waves over a face and performs facial recognition basedon reflections of the ultrasonic waves from the face.
 2. The electronicdevice of claim 1, further comprising: a housing, wherein the ultrasounddevice is disposed within the housing.
 3. The electronic device of claim2, wherein the ultrasound device is an ultrasound-on-a-chip device. 4.The electronic device of claim 3, wherein: the ultrasound transducersoperate in a plurality of frequency ranges, and the electronic circuitryenables a user to select an operating frequency within a selected one ofthe plurality of frequency ranges.
 5. The electronic device of claim 4,wherein the electronic circuitry controls the ultrasound transducers toperform an initial lower-resolution scan at a relatively lower frequencyand a subsequent higher-resolution scan at a relatively higherfrequency.
 6. The electronic device of claim 2, wherein the ultrasounddevice: transmits the ultrasonic waves, through air, to the face, andreceives, through the air, the reflections of the ultrasonic waves fromthe face.
 7. The electronic device of claim 6, further comprising: amemory device that stores a reflection pattern corresponding to a knownface of a person; and electronic circuitry that compares the reflectionpattern stored in the memory device to a pattern corresponding to thereflections received by the ultrasound device.
 8. The electronic deviceof claim 6, wherein the ultrasound device comprises a transmitter thattransmits a pattern, corresponding to the reflections, to an externalprocessor coupled to an external memory device, and the ultrasounddevice determines whether the pattern corresponding to the reflectionsmatches a pattern stored in the external memory device.
 9. Theelectronic device of claim 2, wherein the electronic device is asmartphone device, and the ultrasound device is an ultrasound-on-a-chipdevice.
 10. The electronic device of claim 9, further comprising: amemory device that stores a reflection pattern corresponding to a user;and electronic circuitry that compares the reflection pattern stored inthe memory device to a pattern corresponding to the reflections receivedby the ultrasound device, wherein the electronic circuitry determineswhether the user is authorized to access restricted functions of aprocessor of the smartphone device.
 11. The electronic device of claim9, wherein the ultrasound device operates in at least one frequencyrange selected from a group consisting of: 50 kHz to 100 kHz, 100 kHz to200 kHz, 200 kHz to 300 kHz, 300 kHz to 400 kHz, and 400 kHz to 500 kHz.12. The electronic device of claim 1, wherein the electronic circuitrycontrols the ultrasound transducers to perform a calibration operationthat determines transmission and reception artifacts due toirregularities of the display screen.
 13. The electronic device of claim12, wherein the irregularities include one or both of: surfaceirregularities of the display screen, and internal irregularities of amaterial forming the display screen.
 14. The electronic device of claim12, wherein, based on the calibration operation, the electroniccircuitry compensates for the irregularities by controlling one or bothof a phase and a timing of an ultrasonic wave emitted from one or moreof the ultrasound transducers such that ultrasonic waves that haveuniform wavefronts are transmitted to the face.
 15. The electronicdevice of claim 12, wherein, based on the calibration operation, theelectronic circuitry compensates for the irregularities by correctingthe signals received from the ultrasound transducers.
 16. An electronicdevice, comprising: a housing; and an ultrasound device that is anultrasound-on-a-chip device, comprising: ultrasound transducers; andelectronic circuitry that transmits signals to and receives signals fromthe ultrasound transducers, wherein the ultrasound device electronicallyscans ultrasonic waves over a face and performs facial recognition basedon reflections of the ultrasonic waves from the face, the ultrasounddevice is disposed within the housing, the housing comprises a displayscreen, the ultrasound device scans the face by transmitting ultrasonicwaves through the display screen, and the electronic circuitry controlsthe ultrasound transducers to perform a calibration operation thatdetermines transmission and reception artifacts due to irregularities ofthe display screen.
 17. The electronic device of claim 16, wherein,based on the calibration operation, the electronic circuitry compensatesfor the irregularities by controlling one or both of a phase and atiming of an ultrasonic wave emitted from one or more of the ultrasoundtransducers such that ultrasonic waves that have uniform wavefronts aretransmitted to the face.
 18. The electronic device of claim 16, wherein,based on the calibration operation, the electronic circuitry compensatesfor the irregularities by correcting the signals received from theultrasound transducers.